Re: [Xen-devel] [PATCH for 4.6 13/13] xen/iommu: smmu: Add Xen specific code to be able to use the driver

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Manish,

On 18/02/2015 01:02, Manish wrote:
> On 17/12/14 1:38 am, Julien Grall wrote:
> > The main goal is to modify as little the Linux code to be able to port
> > easily new feature added in Linux repo for the driver.
> >
> > To achieve that we:
> >      - Add helpers to Linux function not implemented on Xen
> >      - Add callbacks used by Xen to do our own stuff and call Linux ones
> >      - Only modify when required the code which comes from Linux. If so a
> >      comment has been added with /* Xen: ... */ explaining why it's
> >      necessary.
> >
> > The support for PCI has been commented because it's not yet supported by
> > Xen ARM and therefore won't compile.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > ---
> >   xen/drivers/passthrough/arm/Makefile |   1 +
> >   xen/drivers/passthrough/arm/smmu.c   | 668
> > +++++++++++++++++++++++++++++++----
> >   2 files changed, 602 insertions(+), 67 deletions(-)
> >
> > diff --git a/xen/drivers/passthrough/arm/Makefile
> > b/xen/drivers/passthrough/arm/Makefile
> > index 0484b79..f4cd26e 100644
> > --- a/xen/drivers/passthrough/arm/Makefile
> > +++ b/xen/drivers/passthrough/arm/Makefile
> > @@ -1 +1,2 @@
> >   obj-y += iommu.o
> > +obj-y += smmu.o
> > diff --git a/xen/drivers/passthrough/arm/smmu.c
> > b/xen/drivers/passthrough/arm/smmu.c
> > index 8a6514f..3cf1773 100644
> > --- a/xen/drivers/passthrough/arm/smmu.c
> > +++ b/xen/drivers/passthrough/arm/smmu.c
> > @@ -18,6 +18,13 @@
> >    *
> >    * Author: Will Deacon <will.deacon@xxxxxxx>
> >    *
> > + * Based on Linux drivers/iommu/arm-smmu.c
> > + *    => commit e6b5be2be4e30037eb551e0ed09dd97bd00d85d3
> > + *
> > + * Xen modification:
> > + * Julien Grall <julien.grall@xxxxxxxxxx>
> > + * Copyright (C) 2014 Linaro Limited.
> > + *
> >    * This driver currently supports:
> >    *    - SMMUv1 and v2 implementations
> >    *    - Stream-matching and stream-indexing
> > @@ -28,26 +35,154 @@
> >    *    - Context fault reporting
> >    */
> <<<snip >>>
>
> > +/* Xen: Dummy iommu_domain */
> > +struct iommu_domain
> > +{
> > +    struct arm_smmu_domain        *priv;
> > +
> > +    /* Used to link domain contexts for a same domain */
> > +    struct list_head        list;
> > +};
> > +
> > +/* Xen: Describes informations required for a Xen domain */
> > +struct arm_smmu_xen_domain {
> > +    spinlock_t            lock;
> > +    /* List of context (i.e iommu_domain) associated to this domain */
> > +    struct list_head        contexts;
> > +};
> > +
> > +/* Xen: Information about each device stored in dev->archdata.iommu */
> > +struct arm_smmu_xen_device {
> > +    struct iommu_domain *domain;
> > +    struct iommu_group *group;
> > +};
> > +
> > +#define dev_archdata(dev) ((struct arm_smmu_xen_device
> > *)dev->archdata.iommu)
> > +#define dev_iommu_domain(dev) (dev_archdata(dev)->domain)
> > +#define dev_iommu_group(dev) (dev_archdata(dev)->group)
> > +
> > +/* Xen: Dummy iommu_group */
> > +struct iommu_group
> > +{
> > +    struct arm_smmu_master_cfg *cfg;
> > +
> > +    atomic_t ref;
> > +};
> > +
> The naming needs to be revisited in this patch. Original driver from
> Will has arm_smmu_domain. This patch adds  iommu_domain,
> arm_smmu_xen_domain, iommu_group.
I can't change the naming of the structure. iommu_domain and iommu_group 
are from Linux. As we don't have it on Xen, I have to add dummy 
structure for it.
> Could you please add some description about the relation and hierarchy
> of these data structures.
Good point, I will try to add more comment and explain why we have to do it.

Regards,

--
Julien Grall

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